1. Field of the Invention
The invention relates to a chute of a feed system for a refuse incineration plant having a cutting apparatus. The invention further relates to a method for operating the chute.
2. Discussion of the Prior Art
Refuse incineration plants are generally fed via a so-called feed system: the refuse is conveyed out of a hopper into a chute and onward into a metering device at the end of the chute. The metering device finally provides good metering of the refuse to the furnace.
To prevent the penetration of secondary air, chutes of considerable length (height up to and greater than 10 m) are used, through which the refuse is conveyed solely through the force of gravity.
Again and again, relatively large objects become jammed or clamped in the chute, and refuse sliding down behind such objects is no longer able to free them from such a position. Such objects then have to be removed from the chute by hand, which disrupts the operating cycle, entails an increased risk of accidents and may lead to the penetration of secondary air which has an adverse effect on incineration and emissions.
The object of the present invention is to provide a chute in which large objects no longer lead to operational disruption, and to provide a method for operating such a chute.
A clamping slide of a cutting apparatus of a chute can be displaced toward a mating holder until they come into contact. This mating holder may be designed as a separate element but may also be formed, for example, by part of a wall of the chute. If, during displacement of the clamping slide toward the mating holder, a relatively large object becomes jammed between the mating holder and the clamping slide, a gap remains open between the two components, and the clamping slide does not reach its closed position. In this event, a cutting slide, which is arranged beneath the clamping slide and the cutting edge of which can be displaced beyond the gap, can be activated so as to cut off that part of the object which projects downward out of the gap. If the clamping slide and the cutting slide are displaced back into their open position, they open up the cross section of the chute, and that part of the object which remains in the gap falls into the chute.
If the mating holder is also designed as a slide element, and if the mating holder and the clamping slide can be moved toward one another on a common plane of movement, there is less risk that, during displacement of the two slide elements, large objects will be carried along sideways over a relatively great distance and consequently will become wedged in place. Moreover, the refuse is released from the center of the chute.
The highly efficient comminution of objects which are clamped in the gap is obtained if the cutting slide can be displaced along a plane which is directly beneath the plane of movement and parallel to the latter. This efficiency can be increased still further if the cutting edge of the cutting slide can be adjusted by means of an adjustment device in such a way that it moves directly along the bottom side of the mating holder.
A cutting edge which is of V-shaped design, and surrounds that part of the object which is to be cut off prior to cutting, from the sides, ensures that that part of the object is cut off, rather than squeezed out, which would require a higher force and therefore a greater outlay on energy.
It is particularly advantageous to close off the chute by means of the cutting apparatus in an at least approximately scaled manner. In this way, in addition to cutting large objects, the cutting apparatus can also be used as a closure device which prevents the penetration of secondary air. This enables the supply of combustion air to be controlled more successfully and therefore results in better combustion, reduced emissions of pollutants, more homogeneous temperature profiles and lower thermal loads in the combustion chamber.
A sealing slide which is arranged beneath the cutting apparatus and is at a distance therefrom can close off the chute so as to form a seal while the cutting apparatus is open. The sealing slide and the cutting apparatus can be used in the manner of a lock, which is particularly advantageous if the refuse incineration plant is to be operated under substoichiometric conditions. In this way, the plant can be rendered inert very efficiently, for example by injecting an inert gas, for example nitrogen, into a lock chamber which is delimited by the sealing slide and the cutting apparatus. This cushion of nitrogen makes it possible to virtually completely seal off the furnace from the atmosphere. The furnace can then be rendered completely inert by injecting further nitrogen.
That section of the chute which is delimited by the sealing slide and a base arranged at the bottom end of the chute has a considerably larger volume than the lock chamber. Consequently, there is always sufficient space beneath the scaling slide for the refuse which falls down out of the lock chamber, and the movement of the sealing slide is not impeded by the refuse.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.